- From: Xan Gregg <xan.gregg@jmp.com>
- Date: Thu, 1 Apr 2004 09:25:14 -0500
- To: www-xml-schema-comments@w3.org
- Cc: Mary Holstege <holstege@mathling.com>, Dave Peterson <davep@iit.edu>
How are multiple pattern facet children represented in the schema
component infoset? The pattern facet schema component has a value
which is a regular expression. So presumably, that value is the
disjunction of all patterns among the children. Is that so? How is
the disjunction written? "p1|p2|p3", for instance?
What about pattern facets at different levels in the derivation? The
rec says they are effectively ANDed together, but how is that
represented in the schema infoset, as there is no conjunction operator
in the regex language? Is the schema processor to figure out the
conjunction? Or do the base and derived patterns stay separate, with
the processor required to walk the base chain for the ANDing? Or are
there multiple pattern facets in the component model? I'm guessing the
patterns at different derivation steps stay separate, but it's only a
guess.
Relevant part of rec (part 2):
Schema Representation Constraint: Multiple patterns
If multiple <pattern> element information items appear as [children]
of a <simpleType>, the [value]s should be combined as if they appeared
in a single ·regular expression· as separate ·branch·es.
Note: It is a consequence of the schema representation constraint
Multiple patterns (§4.3.4.3) and of the rules for ·restriction· that
·pattern· facets specified on the same step in a type derivation are
ORed together, while ·pattern· facets specified on different steps of
a type derivation are ANDed together.
Related member-only thread: Facet equality: questions/issues
http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2004Mar/0187.html
xan
Received on Thursday, 1 April 2004 09:27:07 UTC